The present invention relates to an optical semiconductor device including a multiple quantum well structure of an AlGaInAs system material formed on an InP semiconductor substrate.
The optical fiber communication is characterized by large quantities of transmitted information per one cable, and insusceptibility to electromagnetic waves. Presently the Japan-U.S.A. international telephone circuits, and the domestic major basic circuits are being replaced by optical fibers. Recently the use of optical fiber circuits for individual subscribers is more motivated.
To realize the optical fiber communication for individual subscribers, semiconductor lasers as light sources must be inexpensive. This hinders the use of temperature control means, and expensive optical members, such as light isolators, etc., which are expensive, and the semiconductor lasers require stability to environmental temperature changes, backward light resistance characteristics, etc.
As optical semiconductor lasers of long wavelengths for communication have been used InGaAsP/InP semiconductor lasers including InGaAsP system materials lattice-aligned on InP semiconductor substrates. However, the semiconductor lasers using this InGaAsP system materials has a disadvantage that with environmental temperature changes, a current value required for laser oscillation abruptly rises with a result that the lasers become unusable.
In view of this AlGaInAs/InP system semiconductor lasers including AlGaInAs system materials formed on InP semiconductor substrates as the semiconductor laser materials of long wavelengths which can be expected to improve temperature characteristics is noted, and the following report is made by C. E. Zah, Z. Wang, M. C. Wang, et al.
1) C. E. Zah et al., "Low Threshold 1.3 .mu.m Strained-Layer Al.sub.x Ga.sub.y In.sub.1-x-y As/InP Quantum Well Lasers", IEE Electron. Lett., vol. 28, No. 25, pp. 2323-2325, Dec. 1992
2) C. E. Zah et al, "Low Threshold 1.3 .mu.m Strained-Layer Al.sub.x Ga.sub.y In.sub.1-x-y As/InP Quantum Well Lasers", 13th International Semiconductor Laser Conference, K-5, pp. 202-203, 1992
3) C. E. Zah et a, "High-performance uncooled 1.3 .mu.m Al.sub.x Ga.sub.y In.sub.1-x-y As/InP strained-layer quantum-well laser for subscriber loop applications", IEEE J. Quantum Electron, vol. 30, No. 2, pp 511-523, Feb. 1994
4) Z. Wang et al, "High speed, ultra noise, tensile strained InGaAlAs MOW lasers emitting at 1300 nm for optical communication and microwave applications", IEE Electron. Lett., vol. 30, No. 17, pp. 1413-1414, Aug. 1994
5) C. E. Zah et a;, "High-performance uncooled 1.3 .mu.m Al.sub.x Ga.sub.y In.sub.1-x-y As/InP strained-layer quantum-well lasers for fiber-in-the-loop applications", 94 OFC, pp. 204-205, 1994
6) Z. Wang et al, "High-reliability, high-performance, low-cost coaxial laser module at 1.3 .mu.m for local-loop applications", 94 OFC, pp. 145-146, 1994
7) C. E. Zah et al, "Higher-temperature modulation dynamics of 1.3 .mu.m Al.sub.x Ga.sub.y In.sub.1-x-y As/InP compressive-strained multiple-quantum well lasers", 14th International Semiconductor Laser Conference, Th1. 3, pp. 215-216, 1994
8) Z. Wang et al, "Ultrahigh temperature and ultrahigh speed operation of 1.3 .mu.m strain-compensated AlGaInAs/InP uncooled laser diodes", IEE Electron. Lett., vol. 31, No. 18, pp. 1584-1585, Aug. 1995
However, unless the AlGaIns/InP system semiconductor lasers have suitable structures, the AlGaInAs/InP system semiconductor lasers can have only the same temperature characteristics as the InGaAsP/InP system semiconductor lasers. According to the reports so far made, no AlGaInAs/InP system semiconductor laser having required good temperature characteristics has not yet been provided.